Depth control for search torpedo

ABSTRACT

953,730. Torpedoes. CLEVITE CORPORATION. March 1, 1957 [March 2, 1956], No. 6990/57. Drawings to Specification. Heading B7A. [Also in Division G3] A torpedo is caused to follow a target by acoustic signals transmitted from the torpedo and reflected back from the target. After launching, the torpedo initially follows a spiral scarce path, upwards and downwards between two predetermined levels, until echo signals are received from the target. The latter terminate the spiral search path and cause the torpedo to follow the target. The elevating surfaces are positioned by a servosystem which is controlled by an electrical relay circuit conditioned by the output of a bridge networkresponsive to the echo signals and sensitive to their direction. If the target range is greater than 1100 feet, the torpedo will follow the target in depth and if the target penetrates either the search floor or ceiling the torpedo will move to that level and follow it in azimuth. If a larger echo is received more than six seconds after the previous one the target is regarded as lost and the relay system automatically causes the torpedo to resume the spiral search path until the target is re-located. For target ranges under 1100 feet, the relay system is conditioned by the target echo signals so as to permit the torpedo to pass either the search floor or ceiling levels during pursuit. If a target echo signal is received more than 1 1/2 seconds after the previous one, the target is regarded as lost and the relay system automatically causes the torpedo to proceed in the direction of the last heading.

sept. 1s, 1962 T. E. LYNCH 3,054,371

DEPTH CONTROL FOR SEARCH TORPEDO Filed March 2, 1956 2 Sheets-Sheet 1 Sept. 18, 1962 T. E. LYNCH DEPTH CONTROL FOR SEARCH ToRPEno 2 Sheets-Sheet 2 Filed March 2, 1956 No mlu o ONM Wlu INVENToR. THOMAS E. LYNCH anstatt Patented Sept. 18, 1962 3,054,371 DEPTH CONTROL FDR SEARCH TRPEDO Thomas E. Lynch, Cleveland, Ghia, assigner to Clevite Corporation, Cleveland, Chio, a corporation of Uhio Filed Mar. 2, 1956, Ser. No. 569,053 18 Claims. (Cl. 114-25) This invention relates to a depth control arrangement for a search torpedo.

Search torpedos operate upon the principle of acoustically detecting the presence of a submarine or other target within the effective search range of the torpedo. Prior to detecting the target, the torpedo follows a predetermined search pattern, in which it is seeking to locate the target acoustically. After detecting the target, the torpedo is in the pursuit phase of its operation and is directed toward the target under the control of acoustic signals from the target. In an active search torpedo these target signals are echoes of acoustic pulses transmitted from the torpedo. In a passive search torpedo the target :signals originate as noise generated by the target, such as propeller noise.

The present invention is directed to an arrangement for controlling the depth movement of a search torpedo. This control arrangement causes the torpedo initially to move upward and downward in a predetermined sea-rch pattern Abetween preset depth limits while searching acoustically for a target. When a target signal is received the torpedo abandons its search pattern and proceeds to pursue the target. By virtue of a novel memory in the present control, the torpedo remembers the depth information most likely to enable it to relocate the target if it loses acoustic contact with the target. If the target is at long range, this memory remembers the depth direction in which the torpedo was headed when it rst located the target. If the torpedo loses this target at long range, the memory causes the torpedo to resume its search pattern in this depth direction. However, if the target is at short range, the memory remembers the depth direction in which the torpedo is headed under the control of the target signals. If the target is now lost, the memory causes the torpedo -to go into its search pattern in the same depth direction as it was headed when 4it lost the target.

Accordingly, it is an object of the present invention to provide a novel and improved arrangement for controlling the depth movement of a Search torpedo.

Another object of this invention is to provide a novel depth control arrangement for a search torpedo having novel provision for remembering the depth information most likely to enable the target to be relocated if the torpedo loses acoustic contact with a target which it is pursuing.

It is also an object of this invention to provide such a control circuit which is relay-operated throughout and which operates completely from a direct current power supply, such as a battery.

Another object of this invention is to provide a novel control circuit of this type which is relatively inexpensive, which employs standard components and which is relatively easy to service.

Other and further objects and advantages of this invention will be apparent from the following detailed description of a preferred embodiment of the invention, which is illustrated schematically in the accompanying drawings.

In the drawings:

FIGURE 1 is a schematic View showing the depth control mechanism in a search torpedo; and

FIGURE 2 is a simplified circuit diagram of the present depth control circuit for controlling the operation of the FIG. 1 depth control mechanism.

Referring to FIG. 1, the search torpedo has an elongated generally cylindrical hull with a nose section 10 at its forward end, a tail section 11 at its rear end, and a control section between its ends which includes the depth control unit 12.

In the nose section 10 is formed a chamber 13 in which is mounted an electroacoustic transducer 14. A flexible resilient diaphragm 15 of rubber, neoprene, or the like extends across the front of chamber 13 and is exposed to the sea pressure at its outer face. Suitable acoustic energy-transmitting liquid, such as a mixture of silicone fluids, fills the chamber 13 and serves to pass acoustic energy to and from the transducer 14.

Depth Motor Control Over Elevators on Torpedo The depth control mechanism with which the present control circuit is to be used preferably is the same as that disclosed and claimed in the copending application of B. W. Abrams, Serial Number 530,755, filed August 26, 1955, and now U.S. Patent No. 2,997,972, issued August 29, 1961.

At the tail section 11 are located the propellers 16 for propelling the torpedo through the water, upper and lower rudders 17 and 18 for controlling the azimuth steering of the torpedo, and at either side a pivoted elevator 19 for controlling the depth movement of the torpedo. Each of the elevators 19 is suitably coupled to a down solenoid 20 and an up solenoid 21, which in turn are controlled by corresponding relays 22 and 23, respectively. Relay 22 is connected to a iirst mercury switch 24 mounted, by means of a spring clip 24a, on a rocker arm 25 which pivots about pin 26. Relay 23 is connected to a second mercury switch 27 similarly mounted on rocker arm 25 at the opposite side of the pivot 26.

In their normal, horizontal positions both mercury switches 24 and 27 are open, which keeps relays 22 and 23 deenergized. When the rocker arm 25 is pivoted sufliciently clockwise in FIG. l the globule of mercury in switch 24 moves down (to the right in the drawing) to bridge the xed electrodes in this switch, thereby electrically closing switch 24. At this time switch 27 remains open because its electrodes are at the upper end of the switch envelope in this position of the rocker arm and hence are not bridged by the mercury globule. Conversely, when the rocker arm is pivoted a sufficient amount counterclockwise from its position in the drawing, switch 27 closes and switch 24 is open.

The position of the rocker arm 25, on which the mercury switches 24, 27 are mounted, is controlled by a generally L-shaped actuator 28 which carries a transverse pin 29 slidably received in an elongated slot 28a in the upper end of the rocker arm 25. At its other end the actuator 28 is secured to a plate 30, which is pivoted about pin 31.

At one side of this pivot a tension coil spring 32 is secured at one of its ends to the unit consisting of plate 30 and actuator 28. The opposite end of this spring is attached to a nut 33 threadedly mounted on a screw 34, which may be turned through a gear 35 attached to its opposite end. By turning the screw, the position of the nut 33, and hence the tension on spring 32, is adjusted to exert the desired clockwise bias on plate 30 and actuator 28. Gear 35 is mounted to be driven through gear 40 from a reversible depth control motor 41 for changing the tension on spring 32.

At the opposite side of the pivot 31 for the plate 30 is attached a rod 36, which is connected at its other end to the movable end of a corrugated metal bellows 37. Y

The opposite end of this bellows is xedly positioned. At this latter end the interior of the bellows is connected through a hose 38 to the chamber 13 in the nose section of the torpedo. Accordingly, the interior of the bellows 37 receives the transducer liquid at the same pressure as prevails in chamber 13. This liquid pressure in bellows 37 causes the bellows to exert on the unit consisting of plate 30 and actuator 23 a counterclockwise push which is opposed by the clockwise pull exerted by tension spring 32.

In operation, when the depth control motor 41 is energized in one direction to turn screw 34 in the corresponding direction it causes the torpedo to ascend or descend as it circles about, searching for a target. When the torpedo .ascends to a predetermined search ceiling, the depth control motor 41 is energized in the reverse direction to turn screw 34 correspondingly to cause the torpedo to descend as it circles about. When the torpedo descends to a predetermined search floor, the motor 41 is reversed again and the torpedo begins to ascend once more.

The depth control unit operates on the principle of causing the torpedo to assume a path in depth which tends to maintain both mercury switches open. Thus, at the start of the torpedos ascent the depth control motor 41 turns screw 34 in a direction to reduce the tension exerted by spring 32. When this happens, the torque exerted by spring 32 becomes appreciably less than the opposing torque exerted by bellows 37, due to the sea pressure acting through the transducer liquid in chamber 13 and bellows 37. Therefore, plate 30 ,and actuator 28 tilt counterclockwise in the drawing and, through the pin and slot connection 29, 30 to the rocker arm 25, this causes the mercury switches 24 and 27 to tilt with respect to the torpedo (counterclockwise in the drawing). Mercury switch 27 closes, energizing relay 23 which actuates the up solenoid 21 to operate the elevators to cause the torpedo to head upward. The torpedo heads upward at an angle opposite to the tilt of the mercury switches with respect to the torpedo, tending to restore these switches to their horizontal position, at which both switches are open. Upon continued driving of screw 34 in the same direction, the tension exerted by spring 32 is lessened progressively and the torpedo continues to head upward so as to have this spring torque equalized by the torque exerted by the bellows in response to the sea pressure, which lessens as the torpedo continues to climb.

When the torpedo reaches the desired ceiling in depth the depth control motor 41 is reversed, turning screw 34 in a direction to progressively increase the tension on spring 32. When the torque exerted by this spring on the plate 3) and actuator 28 appreciably exceeds the opposing torque exerted bellows 37, rocker arm 25 is pivoted clockwise in the drawing a suicient amount to close mercury switch 24, the other mercury switch 2'/ being open at this time. This energizes relay 22 which actuates the down solenoid 2t) to operate the elevators 19 on the torpedo to cause the torpedo to begin to descend. The torpedo heads downward at an angle opposite to the tilting of the mercury switches relative to the torpedo, tending to restore these switches to their horizontal position, at which both are open. With continued turning of screw 34 in this direction, the tension exerted by spring 32 continues to increase and the torpedo continues to descend in order to have the spring torque equalized by the bellows torque due to increasing sea pressure at greater depths.

Thus, in both ascent and descent the present pressure control arrangement for bellows 37 operates to cause the torpedo to assume the depth called for by the tension exerted by spring 32, as determined by depth control motor 41.

Setting Initial Search Depth for Torpedo Before going into its upwardly and downwardly spiraling search pattern under the control of motor 41, as described, the torpedo after being launched in the water must rst descend to an initial search depth. The initial search depth for the torpedo is pre-set by means of a gear 50 which meshes with gear 35. A screw shaft 51 is connected to gear 50 to turn therewith and carries an internally threaded follower 52. The follower 52 carries a pointer 53 which rides across a xedly positioned, calibrated depth scale 54. Also, the follower 52 carries a cam 55 which operates a precision snap-acting switch 56 in one position of the follower along the screw shaft 51 and which operates a similar switch 57 in another position of the follower along the screw shaft. As described in detail hereinafter, these switches determine the search ceiling and search floor of the torpedo in its search operation. A precision snap-acting switch 221 is also positioned to be operated by the cam 55 in another position of follower 52 along screw shaft 51. Switch 221 determines the ceiling of the torpedo in its attack phase.

The initial search depth is pre-set by turning gear 5G and screw shaft 51 a predetermined amount to position the pointer S3 at the -desired depth setting on scale 54. Such turning of gear 50 also causes gear 35 and screw 34 to turn a corresponding amount and thereby establish a tension on spring 32 which corresponds to the counterbalancing torque which will be exerted by bellows 37 in response to the sea pressure at that depth setting.

Thus, when the torpedo is launched in the water with its initial search depth pre-set, the tension on spring 32 exerts a torque on plate 30 which exceeds that exerted by bellows 37. Consequently, rocker arm 25 tilts clockwise in FIG. l with respect to the longitudinal axis of the torpedo, closing switch 24 and keeping switch 27 open. As a result relay 22 and the down solenoid 20 are energized, operating the elevators 19 to direct the torpedo downward. As the torpedo continues its descent the sea pressure outside the torpedo increases, and iinally, at the depth pre-set on scale S4, the sea pressure is sufhcient to cause the bellows 37 to exert a torque on plate 30 which counterbalances that exerted by tension spring 32, restoring switch 24 to its open condition. The torpedo is now at its initial search dept and hereafter operates solely under the control of motor 41, which up to now has not been operating.

Climb and Dive Relays Which Control Depth Motor Referring to FIG. t2, the energization of the depth control motor 41 is under the control of climb and dive relays C and D, respectively, which are energized alternatively, as described in detail hereinafter.

When the climb relay C is energized its mobile contact c-9 closes on xed contact c-S and connects one terminal of the depth control motor 41 to a +24 volt D.C. terminal 517 through line 60, the now-closed contacts cp-5 and cl2-12 of close pursuit relay CP, and the normally closed contacts 56C and 56a of the search ceiling switch 56. The other terminal of this motor is connected to ground through the normally closed dive relay contacts d-9 and d-10. When energized in this manner the depth control motor 41 rotates in a direction to lessen the tension on the spring 32 in the depth control unit (FIG. l).

When the climp relay is energized its contacts c4 and c-S open and prevent the dive relay D from remaining energized at this time, if it had been energized previously. Alternatively, when the dive relay D is energized its mobile contacts d-9 closes on xed contact d-S and connects the depth control motor 41 through line 63, the nowclosed contacts cp-Z and cp3 of close pursuit relay CP, and the normally closed contacts 57o and 57a of the search floor switch 57 to the +24 volt D.C. terminal 516. When thus energized, the depth control motor 41 rotates in the opposite direction and by such rotation increases the tension on spirng 32 in the depth control unit.

The energization of dive relay D causes its contacts d-4 and d-S to open, thereby preventing climb relay C from remaining energized at this time.

The climb and dive relays C and D, respectively, are

connected to be energized alternatively, either from the memory section or from the signal section in FIG. 2. The memory section is operative to control the climb and dive relays (and thus, the depth control motor 41) during the search phase of the torpedos operation, which begins after the torpedo has descended to its initial search depth. During search the torpedo spirals up and down between its search ceiling and search floor, while the transducer 14 operates to detect acoustically any target within its effective acoustic range. When the transducer detects such a target the pursuit phase of the torpedos operation begins, and the control of the climb and dive relays is transferred from the memory section to the signal section.

Memory Section This section includes a memory-up relay MU and a memory-down relay MD. These relays are connected to be energized alternatively. When the memory-down relay MD is energized the torpedo is caused to spiral downward to its Search floor. Upon reaching the search floor, the memory-up relay MU is energized and the memorydown relay MD de-energizcd, causing the torpedo to spiral upward until it reaches the search ceiling. Then the memory-up relay MU is de-energized and the memorydown relay MD is energized, causing the torpedo again to spiral down to its search Hoor. This sequence is repeated until the torpedo acoustically detects a target, at which time the signal section takes control over the steering of the torpedo.

During its initial dive the torpedo levels out as it approaches the initial search depth and when the torpedo has assumed a nose-down angle of about 17 to the horizontal a switch (not shown) closes which enables all of the 24 volt circuits in FIG. 2.

A double-pole, double-throw Up-Down switch 70 (FIG. 2) is pre-set before the torpedo is launched, so that the torpedo initially will go into either a downwardly spiraling search pattern or an upwardly spiraling search pattern after the closing of the 17 degree switch just mentioned.

Assuming that switch 70 has been set in its Down position, as shown in FIG. 2, the memory-down relay MD is energized initially as follows: from the +24 volt D.C. terminal 71 through the normally closed contacts mit-5 and mir-4 of the now deenergized memory-up relay MU, line 72, the Down contacts of switch 70, and line 304, through the coil of relay MD to ground.

Energization of the memory-down relay MD completes an energization circuit for dive relay D as described in detail hereinafter.

In addition, such .energization of memory-down relay MD completes a holding circuit for itself, as follows: from the +24 volt terminal 71, through the normally closed MU relay contacts mii-5 and mii-4, and through the now-closed MD relay contacts md-Z and mii-3.

Energization of memory-up relay MU at this time is prevented because the opening of the MD relay contacts m'd-S and rnd-4 breaks the lock-in circuit for relay MU from terminal 71 by way of MD relay contacts mtl-5 and mal-4 and MU relay contacts mil-2 and mit-3.

Alternatively, if switch 70 has been set in its Up position the memory-up relay MU is energized initially as follows: from the +24 volt D C. terminal 71 through the normally closed MD relay contacts and mai-5 and rnd-4, line 73, and the Up contacts of switch 70, through the coil of relay MU to ground.

Energization of the memory-up relay completes an energization circuit for the climb relay C as described in detail hereinafter.

Also, such energization of memory-up relay MU completes a holding circuit for itself, as follows: from the +24 volt D.C. terminal 71, through the normally closed MD relay contacts rnd-5 and mii-4, and the now-closed MU relay contacts mtl-2 and mil-3.

Energization of relay MD at this time is prevented because the opening of the MU relay contacts mu-S and mil-4 breaks the lock-in circuit for relay MD from terminal 71 by way of MU relay contacts mii-5 and mil-4 and MD relay contacts md-2 and Ind-3.

Director and Pursuit Relays The energization of the climb and dive relays is under the control of director relay R, which is connected to be energized from a +24 volt D.C. terminal 75 through the normally open contacts p-Z and p-3 of pursuit relay P. When the pursuit relay is energized as described in detail hereinafter, it closes its contacts p-2 and p-3 and energizes director relay R.

Memory-Section Control Over Climb and Dive Relays Energization of director relay R while the memorydown relay MD is energized completes an energization circuit for the dive relay D as follows: from the +24 volt D.C. terminal 212, through the normally closed contacts .SL-3 and s-9 of signal relay S in the signal section, lines 400 and 408, through the normally-closed MU relay contacts mii-10 and mit-9, the now-closed MD relay contacts rml-9 and Ind-S, line 77, the now-closed R relay contacts r-S and r-9, and line 12S.

Alternatively, energization of Idirector relay R while the memory-up relay MU is energized completes an energization circuit for the climb relay C as follows: from the +24 volt DC. terminal 212, through the S relay contacts s-S and 5 9, lines 400 and 403, through the normally closed MD relay contacts mol-10 and mrt-9, the noW- closed MU relay contacts mil-9 and mit-8, line 78, the now-closed R relay contacts P13 and r-6, and line 123.

Signal Section Turning now to the Isignal section of `the FIG. 2 cirtcuit, there are provided a signal relay S, a signal-up relay SU, and a `signal-down relay SD. Before an acoustic target signal is received by the transducer each of these relays is energized, as follows:

The signal relay S, the signal-up relay SU and the signal-down relay SD are under the control of a keying relay K, which is connected to a keying pulse source 200. The keying pulse source loperates .to deliver a pulse to the keying relay K one each second. When the keying relay K is energized by such a keying pulse it closes its contacts k-S and k-4 and its contacts k-9 and k-3. A high positive voltage from the +750 volt D.C. terminal 87 is applied through these K relay contacts and a 100,000 ohm resistor 88 to the screen grid 84 of pentode tube 82, which controls the energization of signal relay S, yand to the screen grid 89 of pentode tube 90, which controls the energization of the signal-down relay SD, and to the screen grid 91 of the pentode tu-be 92, which controls the energization of the signal-up relay SU. Also, this same positive voltage is applied through these K relay contacts, a 100,000 ohm resistor 93 and line 93a to the terminal 4 of a comparator bridge through which the target echo signals received by the transducer 14 are applied to the signal section. The details of this bridge are omitted in order to simplify this description since such details are considered unnecessary `to an understanding of the present invention. Suce it to say that the applic-ation of this high positive voltage to the bridge terminal 4 results in a positive voltage at the bridge terminal 2, which is applied through resistor 94 to the control Igrid 95 of tube 92, and a positive voltage at the bridge terminal 3, which is applied thro-ugh resistor 96 t-o the control grid 97 of tube 90, and .a positive Vol-tage at the bridge terminal 1, which is applied through resistor to the control grid 83 tube 82.

Accordingly, when the keying relay K is energized, each of the tubes 82, and 92 conducts, due to the application of positive voltages to their respective control and screen grids.

The coil of the signal relay S has one of its terminals connected` through resistor 80 to a +750 volt D.C. terminal 81 and -its other terminal connected to the anode 82a of tulbe 82. When tube 32 conducts in response -to energization of keying relay K, relay S is energized. When relay S is energized in this manner its contacts s-2 and s-3 close, connecting the cathode S2!) of tube 82 directly to ground and bypassing the cathode resistor 86. r[his maintains tube 82 conducting sutiicient current to keep relay S energized after keying relay K is deenergized, following its momentary energization by a keying pulse. The signal relay S remains energized throughout the search phase of the torpedos operation, until an acoustic target signal is received by the transducer 14.

The coil of the signal-up relay SU has one of its termin-als connected through a resistor 98 to a +750 volt D.C. terminal 99 and its other terminal connected to the anode 100 of tube 92. When tube 92 conducts in response to energization of keying relay K, relay SU is energized. When relay SU is thus energized its contacts su-Z and sit-3 close and bypass the cathode resistor 92h for tube 92, connecting the cathode 92a of this tube directly to ground. This maintains tube 92 conducting sufcient current to keep relay SU energized after the removal of the positive voltages on the control and screen grids of tube 92 when keying relay K assumes its normal de-energized condition following its momentary energization in response to a keying pulse. The signal-up relay SU remains energized throughout the search phase of the torpedos operation, until an acoustic target signal is received by the transducer 14 from a target at a higher depth level than the torpedo.

In like manner, the signal-down relay SD is initially energized in response to a keying pulse and a holding circuit maintains this relay energized throughout the search phase of the torpedos operation, until an acoustic target signal is received by the transducer 14 from a target at a lower depth than the torpedo. The coil of relay SD has one Iof its terminals connected through a resistor 101 to aV +750 volt D.C. terminal 102 and its other terminal connected to the anode 103 of tube 90. When tube 90 conducts initially in response to the enerrgization of keying relay K, relay SD is energized. Such energization of relay S'D closes its contacts sd-Z and srl-3, shorting across the cathode resistor 104 for tube 90 and grounding the cathode 105 of this tube. This maintains tube 90 sufficiently conductive to keep relay SD energized after the keying relay K resumes its normal de-energized condition, which removes the positive voltages on the control and screen grids of tube 90.

Signal Section Control Over Pursuit and Director Relays The signal relay S controls the energiza-tion of the pursuit relay P as follows: The coil of relay P has one of its terminals connected through a resistor `110 to a +750 volt D.C. terminal 111 and its other terminal connected to the anode 112 of a pentode tube 113. The screen grid 114 of this tube is connected to a +150 volt D.C. terminal 115. The control grid 116 of tube 113 is, connected directly to the S relay contact s-6. Control grid 116 is connected also to `the cathode 117 of this tube through a resistor 118.

When relay S is energized, as described, its grounded mobile Contact s-S separates from con-tact s6, so that the previously grounded control grid 116 assumes the same potential as cathode 117. Also, capacitor 119, which is connected between control -grid 116 land ground, is charged to the potential of cathode 117. With this zero bias on the control grid 116, the current through tube 113 is suicient to energize relay l. Such energization of relay P energizes relay R, which operates to put the climb and dive relays C and D under the control of the memory section. This condition prevails throughout the search phase of the torpedos operation, until a target signal is received by the transducer 14.

When relay S is de-energized in response tov a target signal, as described hereinafter, its grounded mobile contact s-S closes on contact s-6, connecting the control grid 116 of tube 113 directly to ground and discharging the capacitor 119. With the control grid 116 grounded, a negative control grid bias is produced on tube 113 by the amount of the voltage appearing across cathode resistor 120 as a result of the voltage-dividing action of resistors 120 and 120a. This reduces the current through tube 113 to a value insutlicient to maintain relay P energized. The de-energization of relay P results in the deenergization of relay R, which operates to transfer the control of the climb and dive relays C and D from the memory section back to the signal section, as described in detail hereinafter.

The next keying pulse following a target signal will result in the energization again of signal relay S. However, such energization of relay S does not immediately energize relays P and R because of the time delay provided by the R-C circuit associated with tube 113. This R-C circuit is composed primarily of capacitor 119 and resistor 118, and by appropriate selection of these components there is established a time delay of about six seconds before capacitor 119 charges up suinciently to cause tube 113 to conduct enough current to energize relay P following the energization of relay S in response to a keying pulse.

lf the next target signal is received during this delay interval, the keying relay K will be ineffective to transfer control of the climb and dive relays from the signal section back to the memory section.

However, if during this delay interval the next target signal is not received, it can be assumed that the target has been lost acoustically. Consequently, after this time delay interval the keying relay K will be etlective to transfer the control of the climb and dive relays from the signal section back to the memory section, so that the search phase of the torpedos operation will be resumed.

The memory relay, MU or MD, which was energized before the signal section took over control of the torpedo (and thus was controlling the torpedos depth movement then), remains energized while the signal section is controlling the torpedo. If the torpedo now becomes lost acoustically, this energized memory relay, MU or MD, takes over the depth control of the torpedo.

The only exception to this is if the torpedo has been under the control of the MU relay and then happened to reach the search ceiling while under the control of the signal section. In that event, the search ceiling switch 56 is operated to connect its mobile contact 56a to xed contact 56b, which connects the +24 volt D.C. terminal 59 directly to the coil of relay MD by way of lines 305 and 304, energizing relay MD and thereby breaking the holding circuit for relay MU.

While under the control of the signal section during long range attack (more than 1100 feet) the torpedo is prevented from penetrating the search floor. When the torpedo descends to the search iloor, depth switch 57 is operated to close its mobile contact 57a 0n xed contact 57b, disconnecting the +24 volt D.C. terminal 516 'from the depth control motor 41 to de-energize this motor and cause the torpedo to level oit at this depth. The torpedo will continue to follow the target in azimuth, even while the target remains below the search floor.

Signal Section Control Over Climb and Dive Relays The comparator bridge in the signal section is suitably' istic will also produce a momentary negative voltage pulse at terminal 2 of the comparator bridge, which is connected to the control grid 95 of tube 92, which controls the operation of signal-up relay SU. Conversely, if the target is below the torpedo a momentary negative Voltage pulse will be produced at bridge terminal 3, leading to the control grid 97 of tube 90, which controls the operation of signal-down relay SD.

Up Signal When a signal is received from a target above the torpedo the momentary negative voltage applied from the comparator bridge terminal 2 to the control grid 95 of tube 92 reduces the current through this tube so that the signal-up relay SU is de-energized. This deenergization of relay SU re-inserts the cathode resistor 92h in the circuit for tube 92, so that the current through this tube remains insuicient to energize relay SU even after the momentary negative signal pulse applied to control grid 95 ceases. This condition prevails only until the next keying pulse, however.

At this time, the signal-down relay SD remains energized. The de-energization of relay SU causes the latters contacts sttand sit-6 to close, thereby applying +24 volts D.C. from terminal 125 directly to one end of resistor 300. The other end of resistor 300 is connected directly to the anode 103 of the control tube 9i) for relay SD. Therefore, resistor 390 is now substantially in parallel with tube 90, and the effective resistance in Series with the coil of relay SD is greatly reduced. This insures that suicient current will ilow through the relay SD to keep it energized for the rest of the keying interval.

Also, the signal relay S is de-energized because of the momentary application of a negative voltage from comparator bridge terminal 1 to the control grid 83 of tube 82, which reduces the current through this tube to a value insufficient to maintain relay S energized. When relay S is de-energized in this manner, the opening of the S relay contacts s-2 and s-3 has the effect of reinserting the cathode resistor 86 in the circuit of tube 82, to maintain the tube current reduced even after the mo# mentary negative signal pulse has terminated. Therefore, relay S remain de-energized for the rest of the keying interval.

The de-energization of relay S results in the de-energization of pursuit relay P and director relay R, as described.

Accordingly, the climb relay C receives its energiza-t tion from the signal section as follows: from the +24 volt D.C. terminal 420 through the now-closed contacts sti-5 and .sd-4 of energized relay SD, line 121, the normally closed contacts sii-9 and stt-8 of de-energized relay SU, line 122, the normally closed contacts r-7 and r-6 of de-energized relay R, and line 123.

Energization of dive relay D at the same time climb relay C is energized is prevented in the following manner:

The drive relay D is connected to receive its energization from the +24 volt terminal 125, through the signalup relay contacts su-S and .su-4, line 126, the signal-down re'lay contacts sdf-9 and sd-8, line 127, the director relay contacts r-lil and r-9, and line 128. With the signal-up relay SU de-energized in response to a signal, the SU relay contacts slt-5 and slt-4 are separated and this energization circuit for dive relay D is broken at these contacts, as well as at the contacts sal-9 and .sd-8 of the now-energized signal-down relay SD.

The neXt keying pulse following the Up target signal will re-energize relays S and SU. Therefore, the contacts .su-8 and sit-9 in the energization circuit for climb relay C are opened. However, this does not de-energize relay C because the energization of relay S completes a holding circuit for relay C, as follows: from the +24 volt terminal 212 through the S relay contacts s-S and s-7, line 217, close pursuit relay contacts cp-9 and cp-S, line 218, director relay contacts r-2 and r-1, line 219, the dive relay is contacts d-4 and d-S, and the climb relay contacts c-2 and c-3. Accordingly, the climb relay remains energized following this keying pulse until the director relay R is energized.

This last-mentioned holding circuit is incomplete during the brief time when the mobile signal relay contact .s-8 disengages from xed contact s-9 and moves into engagement with s-7. To prevent the de-energization of the climb relay during this time, there is provided a capacitor 310 connected between director relay contact r-1 and ground. When the climb relay is rst energized, capacitor 319 charges to +24 volts. While the S relay contact s-S is moving from s-9 to s-7, capacitor 310 discharges through the coil of relay C and keeps it energized until s-S contacts s-'7.

Down Signal Alternatively, when a signal is received from a target below the torpedo the negative voltage pulse at terminal 3 of the comparator bridge is applied as a momentary negative voltage on the control grid 97 of tube 90. The current through tube is reduced to a value insuihcient to maintain the signal-down relay SD energized. This de-energization of relay SD has the effect of reinserting the cathode resistor 104 in the circuit of tube 96', so that the current through this tube remains insufficient to energize relay SD even after the momentary negative voltage on grid 97 has terminated. This condition prevails only until the next keying pulse, however.

At this time relay SU remains energized. The deenergization of relay SD results in the closing of its contacts .sd-5 and sal-6. As a result of the +24 volt D.C. terminal 424i is connected directly to one end of resistor 301, which has its other end connected directly to the anode 100' of the control tube 92 for relay SU. In effect, therefore, resistor 301 is substantially in parallel with tube 92, and the effective resistance in series with the coil of relay SD is thereby reduced. This insures that suicient current will continue to ow through relay SU to keep it energized for the remainder of the keying interval.

Signal relay S also is de-energized in response to this target signal in the same manner as just described, with the result that pursuit relay P and director relay R are de-energized.

Therefore, the dive relay D receives its energization from the signal section as follows: from the +24 volt D.C. terminal 125, through the now-closed contacts .ru-5 and .su-4 of energized relay SU, line 126, the normally closed contacts .sd-9 and .rd-S of de-energized relay SD, line 127, the normally closed contacts r-ltl and r-9 of relay R, and line 128.

With the dive relay D energized in this manner, the climb relay C is kept de-energized as follows:

The climb relay is connected to receive its energization from the +24 volt D.C. terminal 421), through the SD relay contacts .rd-5 and .sd-4, line 121, the SU relay contacts slr-9 and stieg, line 122, the director relay contacts r-'7 and r-6, and line 123. This energization circuit is now broken at the contacts sal-4 and sal-S of the now-de-energized signal-down relay SD and at the contacts .ru-9 and stt-8 of the now-energized signal-up relay SU.

The next keying pulse following the down target signal will re-energize relays S and SD. Therefore, contacts .sd-3 and .sd-9 in the energization circuit for dive relay D are opened. However, this does not de-energize relay D because the energization of relay S completes a holding circuit for relay D as follows: from the +124 volt terminal 212 through the S relay contacts s-S and .si-'7, line 217, control relay contacts cp-9 and cp-S, line 218, director relay contacts r-2 and r-l, line 219, the normally open climb relay contacts 0 4 and c-S, and the now-closed dive relay contacts d-2 and d-3. Therefore, the dive relay D remains energized following the keying pulse until the director relay R is energized.

This holding circuit is incomplete during the brief instant when S` relay contact s8 is disengaged from s-9 and not yet in engagement with s-7. Capacitor 310, which was charged to +24 volts when the dive relay was iirst energized, discharges through the dive relay and keeps the latter energized during this short interval until s-S engages s7.

Control Section The control section in FIG. 2 is made up of the blanking relay B, the close pursuit relay CP, the search ceiling switch 56 and the search floor switch 57, the azimuth relay A and the pursuit ceiling switch 221.

Blanking Relay The blanking relay B has one side of its coil connected through line 400 to the signal relay Contact s-9. The other side of the B relay coil is connected to a contact 401 which engages a rotary commutator 402, which has its shaded segment grounded. Commutator 402 is suitably driven to rotate one full turn (counterclockwise in FIG. 2) after an acoustic pulse is transmitted by the transducer 14. The commutator starts from the position shown in FIG. 2 and for a period of about 1/2 second after the pulse is transmitted the contact 401 engages the grounded portion of the commutator.

Every time an echo is received by the transducer 14 the signal relay S is de-energized, as described, connecting one side of relay B to the +24 volt D C. terminal 212 through line 400 and the signal relay contacts s-9 and .r-S. If this echo is received within about 1/2 second after the transmitted signal pulse the other side of relay B is grounded through contact 401 and commutator 402. This happens if the target is at short range, within about 1100 feet of the torpedo.

However, if the echo is not received within this brief time interval the commutator 402 will have rotated to position its ungrounded segment against contact 401, thereby preventing relay B from becoming energized.

This condition occurs if the target is at long range, more than about 1100 feet away from the torpedo.

The initial energization of relay B through commutator 402, as described, causes its contacts b-S and b-12 to close, and likewise its contacts b-2 and b-3. This cornpletes a holding circuit for relay B as follows: from the +24 volt D.C. terminal 75 at relay P, through the P relay contacts p-2 and p-l, line 403, the B relay contacts b-2 and b-3, line 404, through the coil of relay B, through the B relay contacts b-12 and b-5 to ground. As already described, relay P is de-energized in response to the deenergization of relay S. However, if relay S is again energized in response to a keying pulse, relay P remains cle-energized for an interval of about six seconds, due to the described R-C circuit associated with its control tube 113. Accordingly, due to this holding circuit, relay B remains energized as long as echoes are being received from targets at short range and for an interval of about six seconds after the last target echo is received.

ln its normal, de-energized condition relay B has its mobile contact b-9 engaging xed contact b-10. This completes an energization circuit for the close pursuit relay CP as follows: from the +24 volt D.C. terminal 405, B relay contacts b-9 and b-10, line 406, through the coil of relay CP to ground.

When relay B is energized it connects the +24 volt D.C. terminal 405 through the B relay contacts b-9 and b-8, and line 407 to the climb and dive relay contacts c-6 and d-6, respectively. Because of this, the climb or dive relay Which is then energized, under the control of the signal section, causes the corresponding memory relay to be energized.

Thus, if the torpedo is heading up, in response to a target signal which resulted in the de-energization of the signal-up relay SU, the climb relay C is energized, as described. This causes the memory-up relay to be energized as follows: from the +24 volt D.C. terminal 405, through the B relay contacts b-9 and b-S, line 407, the C relay contacts c-6 and c-13, line 408, through the coil of relay MU to ground. Such energization of relay MU completes a holding circuit for this relay, as described. With this arrangement, the memory section remembers that the torpedo is heading upward. lf the target is now lost acoustically and control of the climb and dive relays is transferred from the signal section back to the memory section, the memory-up relay MU will cause the torpedo to continue to head upward-the same direction as it was headed when it lost the target.

Alternatively, if the torpedo is heading down, in response to a target signal which resulted in the de-energization of signaldown relay SD, the dive relay D is energized as described. This causes the memory-down relay MD to be energized as follows: from the +24 volt D C. terminal 405, through the B relay contacts b-9 and b-, line 407, the D relay contacts d-6 and d-13, line 409, through the MD relay coil to ground. Such energization of relay MD completes a holding circuit for this relay, as described. Thus, the memory section now remembers that the torpedo is heading downward. lf the target now is lost acoustically and control of the climb and dive relays is transferred from the signal section back to the memory section, the memory down relay MD will cause the torpedo to continue to head downWard--the same direction it was headed when it lost the target.

Azimuth Relay insofar as the depth operation of the torpedo is concerned, azimuth relay A controls holding circuits for the climb and dive relays C and D during short range pursuit of the target (1100 feet or less), as described in detail hereinafter. One terminal of the coil of relay A is connected to a +750 volt D.C. terminal 300. The other terminal of the coil of relay A is connected to the anode 30i of a pentode tube 302. The screen grid 303 of this tube is connected directly to a volt D.C. terminal 304. The control grid 305 of this tube is connected through line 306 directly to contact s-l of the signal relay S. A rst resistor 307 is connected between control grid 305 and the cathode 308 of tube 302. A capacitor 309 is connected between control grid 305 and ground. A

second resistor 310 is connected between the cathode 308' and the +150 volt D C. terminal 304. A third resistor 311 is connected between the cathode 300 and ground.

In the no-signal condition, prior to receiving a target echo, signal relay S is energized and its contactsl s-1 and 5 2 are open. The control grid 305 of tube 302 is at the same potential as the cathode 308 at this time because of its connection thereto through resistor 307. With no control grid bias, the current through tube 302 is sufficient to energize azimuth relay A. Capacitor 309 is charged to the potential at cathode 308.

When a target echo is received, signal relay S is deenergized and the S relay contacts s-1 and s-2 close, grounding the control grid 305 of tube 302 and discharging capacitor 309. With the control grid 305 at ground potential, the potential at cathode 308 is increased by the amount of voltage developed across cathode resistor 311. The increased bias reduces the current through tube 302 to a value insufficient to maintain relay A energized.

At the next keying pulse, signal relay S is again energized, opening its contacts s-l and s-2 and disconnecting the control grid 305 of tube 302 from ground. However, due to the R-C time delay circuit composed essentially of capacitor 309 and resistor 307, relay A remains deenergized for a brief interval. This is because capacitor 309 does not instantaneously charge through resistor 307 to a potential sufcient to cause the tube 302 to conduct enough current to energize relay A. This R-C time delay interval is about 1/2 second, measured from the time that the signal relay S is energized.

if a target echo is received at least once during each keying interval, relay A will remain energized.

Close Pursuit Relay The close pursuit relay CP has one side of its coil connected directly to the blanking relay contact band the other side grounded. Thus, relay CP is energized when relay B is de-energized and is de-energized when relay B is energized.

During the search phase of the torpedos operation (under the control of the memory section, as described) and during the pursuit of a target at long range, relay B is de-energized. At these times relay CP is energized from the -|-24 volt D C. terminal 495 and the B relay contacts [9 9 and b-10. When thus energized, relay CP does the following:

(l) It connects the depth control motor 41 in series with the search ceiling switch 56 or the search floor switch 57, depending upon whether the torpedo is climbing or diving at that time, thereby insuring that the torpedo cannot go above the sea-rch ceiling or below the search lloor during the long range search and long range pursuit phases of its operation. Thus, if the torpedo is diving, the dive relay D is energized and depth control motor 41 is oonnected to the terminal 57a` of search floor switch 57 by way of the now-closed D relay contacts d-9 and d-S, line 63, and the now-closed CP relay contacts cp-Z and cp-S. If the torpedo reaches the search floor, the mobile contact 57a of switch 57 disengages from contact 57C and engages contact 5711. This disconnects depth control motor 41 from the +24 volt D.C. terminal 516 to which the mobile contact 57a is connected. Similarly, if the torpedo is climbing, the climb relay C is energized and depth control motor 41 is connected to the contact 56C of search ceiling switch 56 by way of the now-closed C relay contacts c-9 and c-S, line 60, and the now-closed CP relay contacts cp-5 and cp-12. If the torpedo reaches the search ceiling, the mobile contact 56a of switch 56 disengages from contact 56C and engages contact 561:. This disconnects the depth control motor 41 from the +24 volt D.C. terminal 517 to which the mobile contact 56a is connected.

(2) During long range pursuit, in conjunction with signal relay S and director relay R, relay CP provides an energization circuit for the climb -or dive relay to maintain the latter energized for six seconds after receipt of the last target echo. Thus, if the torpedo is diving, in response to the last target echo received, and relay S is energized in response to the next keying pulse (no new target echo having been received in the meantime), the energized close pursuit relay CP sets up a holding circuit to maintain the dive relay D energized, as follows: from the +24 volt D.C. terminal 212 through the now-closed contacts s-8 and s-7 of signal relay S, line 217, the nowclosed contacts rp-9 and cp-S of close pursuit relay CP, line 218, the normally closed contacts r-2 and r-1 of director relay R, line 219, the normally-closed contacts c-4 and c-5 of climb relay C, the now-closed contacts d-2 and d-3 of dive relay D, line 128, and through the coil of dive relay D to ground. Alternatively, if the torpedo had been climbing in long range pursuit of the target at the time of the last target echo, and relay S is de-energized by the next keying pulse, the energized close pursuit relay CP completes a holding circuit to maintain climb relay C energized, as follows: from the +24 volt D.C. terminal 212 through the signal relay contacts s-S and s-7, line 217, the close pursuit relay contacts cp-9 and cp-S, line 218, director relay contacts r-2 and r-1, line 219, the normally-closed contacts d-4 and d-5 of dive relay D, the now-closed contacts c-Z and c-3 of climb relay C, line 220, through the coil of climb relay C to ground. As already pointed out, a siX second time delay is provided by the R-C circuit associated with the `control tube 113 for pursuit relay P, which serves to maintain the director relay R de-energized for this period following receipt of the last target 14 echo. Therefore, the above-described holding circuit is broken at the end of this six second time delay.

The close pursuit relay CP is de-energized in response to energization of relay B, as described. This happens when the torpedo is in acoustic contact with a target within 1100 feet. When de-energized, relay CP does the following:

(1) It bypasses the search ceiling switch 56, thereby enabling the torpedo to climb labove the search ceiling depth. Thus, if the torpedo is climbing, with relay CP de-energized the energization circuit for the depth control motor 41 is from the +24 volt D.C. terminal 517, through the normally closed contacts 221a and 221e of the attack ceiling switch 221, through the CP relay contacts cp-4 and cp-S, line 60, and the now-closed contacts c-S and c-9 of climb relay C.

However, if the target should ascend to the depth preset by the attack ceiling switch 221, this switch will be operated to separate its mobile contact 221e from xed contact 221C, thereby cle-energizing the depth control motor 41.

(2) It bypasses the search floor switch 57, thereby enabling the torpedo to dive below the search floor depth, provided selector switch 222 is pre-set to permit this to happen. Selector 222 has two alternate positions: if the mobile contact 223 engages the lower stationary contact 224 it puts switch 222 in series with the depth floor switch 17 to receive current from the +24 volt D.C. terminal 516; if mobile contact 223 engages the upper xed contact 225 it is directly connected to the +24 volt D C. terminal 226 and bypasses the depth iloor switch 57. In this latter position of selector switch 222, if the torpedo is diving the depth control motor is energized independent of depth floor switch 57 as follows: from the +24 volt D.C. terminal 226, through the selector switch contacts 225, 223, the CP relay contacts cp-1 and cp-2, line 63, and the now-closed contacts d-S and d-9 of dive relay D.

(3) It shortens to about 11/2 seconds the time delay period during which the torpedo is maintained diving or climbing after the last transmitted sound pulse. This is accomplished by changing the holding circuit for the climb or dive relay (whichever is energized at the time). Thus, during short range pursuit and with relay CP deenergized, if the torpedo is diving the new hol-ding circuit for maintaining the dive relay D energized is as follows: from the +24 volt D C. terminal 212 associated with signal relay S, through the S relay contacts s-S and s-7, line 216, the normally-closed contacts 1 9 and a-8 of azimuth relay A, line 230, the R relay contacts r-2 and r-1, line 219, the normally-closed contacts c-4 and c-5 of climb relay C, the now-closed contacts d-2 and d-3 of dive relay D, line 128, and through the coil of relay D to ground. Alternatively, if the torpedo is climbing the new holding circuit for the climb relay C is as follows: from the +24 volt D.C. terminal 212, through the S relay contacts s-S and s-7, line 216, the A relay contacts 1 9 and a-S, line 230, the R relay contacts r-2 and r-l, line 219, the normally-closed contacts d-4 and d-S of dive relay D, the now-closed contacts c-2 and c-3 of climb relay C, line 220, and through the coil of relay C to ground. In each of these holding circuits the time delay is provided by the R-C delay circuit associated with azimuth relay A. As already described, this R-C circuit maintains relay A energized for a period of about 11/2 seconds after the last transmitted pulse. Following this, relay A is de-energized and breaks the described holding circuit for the climb or dive relay.

Operation In the operation of the present control circuit, when the torpedo is launched in the water it descends to the initial search depth pre-set on the depth scale 54 in FIG. 1, as described in detail previously herein.

Upon reaching the initial search depth the torpedo operates in depth initially under the control of the memory section. Depending upon the setting of Up-Down switch 70, the torpedo will begin to spiral upward or downward. Each time the torpedo reaches its search ceiling, as determined by switch 56, or its search oor, as determined by switch 57, it reverses its direction of travel in depth.

At this time, the relays S, SU and SD in the signal section will have been energized initially in response to the operation of keying relay K and remain energized through their described holding circuits. Due to the energization of signal relay S, the pursuit relay P and the director relay R are also energized, blanking relay B is de-energized, close pursuit relay CP is energized, and azimuth relay A is energized.

While the torpedo is spiraling downward, relay MD is energized and relay MU is de-energized. Accordingly, dive relay D is energized from the memory section, as described in detail hereinbefore, to cause the depth control motor to turn in the direction which makes the torpedo dive.

While the torpedo is spiraling upward, relay MU is energized and relay MD is de-energized. Therefore, the climb relay C is energized from the memory section so as as to cause the depth control motor 41 to turn in the direction which makes the torpedo head upward.

The alternate upward and downward spiral movement of the torpedo under the control of the memory section continues until an acoustic signal is received by the torpedo. Then the torpedo begins to operate under the control of the signal section.

If the signal is received from a target at a depth below that of the torpedo, relays S and SD are de-energized. Such de-energization of relay S causes the pursuit relay P and the director relay R to be de-energized, as described in detail previously. This puts the dive relay D under the control of signal-down relay SD, which operates to energize the dive relay in the manner described in detail previously. Such energization of dive relay D causes the depth control motor 41 to turn in the direction for causing the torpedo to descend.

On the other hand, if the signal is received from a target at a depth above that of the torpedo, relays S and SU are de-energized. With pursuit relay P and director relay R deenergized in response to the de-energization of signal relay S, the climb relay C is put under the control of relay SU. Relay SU operates to energize the climb relay as described in detail previously. Such energization of climb relay C causes the depth control motor 41 to turn in the direction causing the torpedo to climb.

If the signal is received from a target at the same depth as the torpedo, only relay S is de-energized. In this event the torpedo remains under the control of the signal section and follows the target in azimuth.

Long Range Pursuit If the target signal echoes are being received from a target beyond about 110() feet, the blanking relay B will remain de-energized and the close pursuit relay CP will be energized. As already described in detail such energization of relay CP does the following:

(l) puts the torpedo under the control of the search ceiling switch 56 and the search floor switch 57, so that the torpedo cannot go above the Search ceiling depth or (below the search iloor depth; and

(2) sets up a holding circuit for maintaining the climb or dive relay energized for about six seconds after the las-t target echo, so that the torpedo continues to climb or dive during this delay interval. This holding circuit is broken only at the end of the delay interval provided by the R-C circuit associated with the control tube for the pursuit relay P.

lf the torpedo continues to receive target echoes at intervals no greater than about six seconds, it will continue to pursue the target in depth.

If the target should penetrate the search ceiling or the Search floor, the torpedo will rise or descend to that level and then continue to follow the target in azimuth.

If the next target echo is not received within the six second interval it may be assumed that the target has been lost7 acoustically. If this happens relays P and R become energized and transfer the control over the climb and dive relays from the signal section back to the memory section.

The memory relay, MU `or MD, which had been energized just before the signal section took over, now takes over control of the torpedos depth movement, unless it happened that the torpedo penetrated the search ceiling while under the control of the signal section.

Under the renewed control of the memory section the torpedo resumes its upward and downward spiraling search pattern between its Search tloor and Search ceiling until it again locates a target acoustically.

Close Pursuit If the target echoes are being received from a target within about 1100 feet of the torpedo, the blanking relay B will be energized, as described, and consequently the close pursuit relay CP will be de-energized.

Accordingly,

(l) the search ceiling switch 56 and the search iloor switch 57 are bypassed, so that the torpedo can now penetrate either the Search ceiling or the search oor;

(2) a holding circuit is set up which maintains the climb `or dive relay energized for about 11/2 seconds after the last transmitted pulse. This delay interval is established by `the described R-C circuit associated with the control tube 302 for azimuth relay A. (The six second holding circuit associated with relay P is disconnected from the climb and dive relays at this time due to the de-energization of relay CP.)

If the next target echo is not received within the 11/2 second interval it may be assumed that the target has been lost acoustically. If this happens, relays P and R become energized and transfer the control over the climb and dive relays from the signal section back to the memory section.

The memory relay, MU or MD, corresponding to the depth direction in which the torpedo had last |been heading (under the control of the signal section) before losing the target, now takes over the control of the torpedos depth movement.

The memory operation of the present depth control arrangement is extremely important to the successful pertormance of the torpedo. If the target `is lost at long range, the memory causes the torpedo to resume to search in the same direction it was headed when it previously located the target. lf the target is lost at short range, the memory causes the torpedo to Search in the same di rection it was headed at the time it lost the torpedo. The functioning of the memory in both of these situations :insures that the `Search pattern will be resumed in the depth direction most likely to relocate the lost target promptly. I n practice, this has resulted in an improved percentage of hits by the torpedo.

Another important aspect of the present invention is that relays and other standard components are employed throughout and the entire circuit is energized by direct current. Accordingly, the present control circuit is inexpensive and easy to service, as compared with previous circuits for the same general purpose.

While there has been described herein and illustrated schematically in the accompanying drawings a particular embodiment of the present invention, it is to be understood that various modifications, omissions and refinements which depart from `the disclosed embodiment may be adopted without departing from the spirit and scope of the present invention.

I claim:

1. In a search torpedo having provision for receiving target signals, the combination of depth control means controlling the depth movement of the torpedo, a memory ,section having provision for controlling said depth control means to cause the torpedo to move successively upward and downward between predetermined depth limits while searching for a target, a signal section having provision for controlling said depth control means in response to target signals received by the torpedo to cause the torpedo to pursue the target in depth and connected to take over control of said depth control means from the memory section in response to a target signal received by the torpedo, means operative while target signals are being received by the torpedo from a target beyond a predetermined range to maintain said memory section in the same condition it had just before the transfer of control over said depth control means to the signal section, and means responsive to the non-reception of later target signals by the torpedo within predetermined intervals for disconnecting said depth control means from under the control of the signal section and putting said depth control means back under the control of the memory section for depth movement of the torpedo under the re-established control of the memory section in the same direction as before the transfer of control over said depth control means to the signal section.

2. The combination of claim 1, wherein said depth control means, the memory section and the signal section are energized entirely from direct current power supply means.

3. The combination of claim 2, wherein said depth control means comprises a depth control motor and climb and dive relays controlling the energization of the depth control motor, and the signal section comprises relays operable in response to target signals to control the operation of the climb and dive relays.

4. The combination of claim 3, wherein the memory section comprises a memory-up relay yand a memorydown relay connected to -be energized alternatively from said power supply means, and wherein there is further provided means operative while the memory section has control over said depth control means to establish connections from the memory-up relay and the memorydown relay to the climb and dive relays for energizing the climb relay from said power supply means when the memory-up relay is energized and for energizing the dive relay from said power supply means when the memorydown relay is energized.

5. In a search torpedo having provision for receiving target signals, the combination `of depth control means controlling the depth movement of the torpedo, a memory section having provision for controlling .said depth control means to cause the torpedo to move successively upward and downward between predetermined depth limits while searching for a target, a signal section having provision for controlling said depth control means in response to target signals received by the torpedo to cause the torpedo to pursue the target in depth and connected to take over control of said depth control means from the memory section in response to a target signal received by the torpedo, means operative while target signals are being received by the torpedo from a target within a predetermined range to maintain the memory section in condition to establish the same operation of said depth control means as then directed by the signal section, and means responsive to` the non-reception of later target signals by the torpedo within predetermined intervals for disconnecting said depth control means from under the control of the signal section and putting said depth control means back under the control of the memory section for continued depth movement of the torpedo under the re-established control of the memory section in the same direction as it last had under the control of the .signal section.

6. The combination of claim 5, wherein said depth control means, the memory section and the signal section are energized entirely from direct current power supply means.

7. The combination of claim 6, wherein said depth control means comprises a depth control motor and climb and dive relays controlling the energization of the depth control motor, and the signal section comprises relays operable in response to target signals to control the operation of the climb and dive relays.

8. The combination of claim 7, wherein the memory section comprises a memory-up relay and a memory-down relay connected to be energized alternatively from said power supply means, and wherein there is also provided means operative while the memory section has control over said depth control means to establish connections from the memory-up relay and the memory-down relay to the climb and dive relays for energizing the climb relay from said power supply means when the memory-up relay is energized and for energizing the dive relay from said power supply means when the memory-down relay is energized.

9. In a search torpedo having provision for receiving target signals, the combination of depth control means controlling the depth movement of the torpedo, a memory section having provision for controlling said depth control means to cause the torpedo to move successively upward and downward between predetermined depth limits while searching for a target, a signal section having provision for controlling said depth control means in response to target signals received by the torpedo to cause the torpedo to pursue the target in depth and connected to take over control of said depth control means from the memory section in response to a target signal received by the torpedo, means operative while target signals are being received by the torpedo from a target beyond a predetermined range to maintain said memory section in the same condition it had just before the transfer of control over said depth control means to the signal section, and means operative while target signals are being received by the torpedo from a target Within said predetermined range to maintain the memory section in condition to establish the same operation of said depth control means as then directed by the signal section.

l0. The combination of claim 9, wherein said depth control means, the memory section and the signal section are energized, entirely from direct current power supply means.

1l. The combination of claim 10, wherein said depth control means comprises a depth control motor and climb and dive relays controlling the energization of the depth control motor, and the signal section comprises relays operable in response to target signals to control the operation of the climb and dive relays.

l2. The combination of claim 1l, wherein the memory section comprises a memory-up relay and a memorydown relay connected to be energized alternatively from said power supply means, and wherein there is also provided means operative while the memory section has control over said depth control means to establish connections from the memory-up relay and the memorydown relay to the climb and dive relays for energizing the climp relay from said power supply means when the memory-up relay is energized and for energizing the dive relay from said power supply means when the memorydown relay is energized.

13. The combination of claim 9, wherein there is provided means operative in response to the reception of a signal by the torpedo from a target beyond said predetermined range to maintain said depth control means under the control of the signal section for a predetermined interval following the last target signal received by the torpedo, and means operative in response to the reception of a signal by the torpedo from a target within said predetermined range to maintain said depth control means under the control of the signal section `for a preselected 19 shorter interval following the last target signal received by the torpedo.

14. The combination of claim 13, wherein there is provided means operative following the reception of a signal by the torpedo from a target beyond said predetermined range and the later non-reception of such target signals by the torpedo within said predetermined interval for transferring the control over said depth control means from the signal section back to the memory section, and means operative following the reception of a signal by the torpedo from a target within said predetermined range and the later non-reception of such target signals within said preselected shorter interval for transferring the control over said depth control means from the signal section back to the memory section.

15. In a search torpedo, the combination of depth control means controlling the depth movement of the torpedo, direct current power supply means having connections to said depth control means to energize the latter, a memory section comprising relays connected to be energized by said power supply means and connected to control said depth control means to cause the torpedo to move successively upward and downward between predetermined depth limits while searching for a target, and a signal section comprising relays connected to be energized by said power supply means and connected to take over control of the depth control means from the memory section relays in response to a target signal to cause the torpedo to follow the target in depth.

16. In a search torpedo, the combination of direct current power supply means, a reversible depth control motor connected to be energized by said power supply means and connected to control the depth movement of the torpedo, climb and dive relays connected to be energized alternatively by said power supply means and connected to the depth control motor to cause the motor to be energized by said power supply means to turn in one direction when the climb relay is energized for causing the torpedo to move upward and to turn in the opposite direction when the dive relay is energized for causing the torpedo to move downward, a memory section comprising relays connected to be energized alternatively by said power supply means, a director relay controlling the energization of the climb and dive relays, connections from the relays in the memory section through the director relay to the climb and dive relays to control the energization of the climb and dive relays for causing the torpedo to move upward and downward successively between predetermined depth limits while searching acoustically for a target, a signal section comprising a signal relay, a signal-up relay and a signal-down relay responsive to acoustic target signals received by the torpedo, the signal relay being connected to the director relay to control the operation of the director relay, and connections from the signal-up relay and the si gnal-down relay through the director relay to the climb and dive relays for energization of the climb and dive relays from the signal-up and signal-down relays in response to acoustic target signals received by the torpedo.

17. The combination of claim 16, wherein there is additionally provided a keying relay connected to control the energization of the ysignal relay, the signal-up relay and the signal-down relay, the signal relay being operative in response to the keying relay to operate the director relay to connect the climb and dive relays to the relays in the memory section, and the signal relay being operative in response to an acoustic target signal received by the torpedo to operate the director relay to connect the climb and dive relays to the signal-up and signal-down relays.

18. The combination of claim 16, wherein there is additionally provided a keying relay connected to initially energize the signal relay, the signal-up relay and the signal-down relay, holding circuits for maintaining the signal relay, the signal-up relay and the signal-down relay energized following their initial energization in response to the keying relay, the signal relay when energized operating the director relay to connect the climb and dive relays to the memory-up and memory-down relays, respectively, means for de-energizing the signal relay and the signal-up relay in response to a signal received from a target above the torpedo, means for de-energizing the signal relay and the signal-down relay in response to a signal received from a target below the torpedo, the signal relay when de-energized operating the director relay to connect the climb and dive relays to the signal-up and signal-down relays, and delay circuit means maintaining the director relay operative to keep the climb and dive relays connected to the signal-up and signal-down relays for a predetermined time following the last target signal received by the torpedo.

References Cited in the file of this patent UNITED STATES PATENTS 1,121,563 Leon Dec. 15, 1914 1,137,222 Leon Apr. 27, 1915 1,312,510 Baker Aug. 12, 1919 1,816,768 Elia July '28, 1931 1,892,431 Hammond Dec. 27, 1932 2,420,676 Peterson May 2,0, 1947 2,580,834 Prescott Jan. l, 1952 

